The present invention generally relates to ultrasonic transducers, and in particular to phased array ultrasonic transducers.
There continues to be a need for ever more sensitive detection of defects in structurally-critical metal components such as 8-inch titanium alloy or nickel alloy billets from which may be fabricated safety-critical rotating components used in turbine engines and other high-load, high-temperature applications. Ultrasound in the megahertz range is typically used for such inspection because of the ability to achieve relatively high defect resolution in such billets.
For example, U.S. Pat. No. 6,789,427B2 entitled “Phased array ultrasonic inspection method for industrial applications” discloses an inspection method which utilizes an array of transducers, which may be a linear array, to produce an ultrasonic transmission beam focused into a component undergoing inspection. U.S. Pat. No. 5,099,459 issued to Smith discloses a two-dimensional transducer array fabricated by segmenting a piezoelectric material of large elements into smaller elements. U.S. Pat. No. 4,431,936 issued to Fu et al. discloses transducer configurations, including linear arrays and concentric structures, for generating uniform and focused ultrasonic beams.
As can be seen, there continues to be a need for an improved ultrasonic apparatus and method for detecting small defects in billet material.